Hi guys,
I recently bought an aftermarket retrofit delay wiper switch (see image) for 71-73 Mustangs. Since this is a plug-and-play device, there are no special secrets in installing it. Maybe aside from pinning the ground strap to the right point of the dash...

I installed it on my 71 Mach 1, but when I turned the ignition key to RUN position, the switch only made a buzzing sound for a few seconds. Switching it had no effect. Only thing working is the washer pump when pressing on the knob. There is no wiping acion at all, neither in delay nor in low or high speed.

Does anyone have the same switch installed in his/her 71 Mustang with 2-speed wipers and can provide experiences with it?

In the meantime I can test the other option I have. An intermittent system including switch from a mid-80s F150. It also looks like a simple plug-in, but it is not. While the receptcle in the Mustang has 7 contacts, the pigtail plug coming from the intermittent governor only has 6. One is left open.

I can get the Hi and Lo positions running, also wash, but no intermittent and no park yet. I keep testing...

The aftermarket ones are very bad quality control. I have had 3 go bad on me out of 5 purchased. The last one I thought had gone bad but it had not really the wires had starting slipping out of the plug- pushing them back in all the way so the tabs made proper contact and epoxing them in place fixed that.